The Scottish system seems to be much simpler - and more flexible - than the English system.
There is no such thing as reception: children are entitled to free sessions at nursery (either private or state) for 12.5 hours from the term after their third birthday.
Children born between March one year and February the next start school in Primary 1 in mid August of that year. (some areas start half days, some so straight in to full days - but all are full time by the end of September). If your child is not 5 by the start of the school year, you can hold them back unitl the following year. But - crucially - they don't just miss their first year of school as seems to happen in some places in England - they will then start as one of the older kids in that year's Primary 1.
You can also ask for an assessment if you want your child to start early.
So it means that in theory, in the August, the oldest chald will be 5 and 5.5 months (excluding those that were held back) and the youngest would be 4 and 6.5 months. In theory, you could have a child that was just about to turn 6 - but that is the absolute oldest. (My own ds' birthday is 10 September, so we did check whether we thought he was ready to start - but he very definitely was).
Nursery is good for introducing them to slightly more structured learning - but they don't actually start learning to read or do maths until they start P1. But from our introduction to how they are taught (workshop held last night! ), there is still a lot of play and movement and fun in what they do.
I have often said that we start them too young in this country. But having seen the way that ds is being pushed gently - but still "playing" and enjoying what he is doing and thriving on it - I am now more comfortable with it.
I am still horrified by how young they seem to go into the "compulsory" system in England? How young are they when they start in reception - and once they have started, is that you, as parents, into the authorised/unauthorised absence routine? At least an nursery, we still had the choice about when we could take holidays, as there is no issue with taking them out of nursery.